Process of reducing iron ore.



APPLIAIION FILED JUNE 24, 1903'.

K w /|.m\ N .N 1

PATENTED PEB. 1s, 1906.

G. M. WESTMAN.

PROCESS 0F RBDUGING IRON ORE.

APPLICATION FILED JUNE 24, 1903.

2 SHEETS-SHEET 2.

UNITED sTATEs PATENT oEEioE.

GUSTAF M. YORK, N. Y.

PROCESS OF REDUCING lFlON ORE- To all whom it may concern:

Be it known that I, GUs'rAF M. WESTMAN, a subject of the King of Sweden and Norwa residing at New York, countyof New York, and State of New York, have invented certain new and useful Improvements in Processes of Reducing Iron Ore, fully described and represented in the following specification and the accompanying drawings, forming a part of the same.

It has been proposed heretofore to reduce iron ore by subjecting it to the action of highly-heated Water-gas-that is, a gas consisting principally of carbon monoxid and hydrogen. ing materialsuch, for instance, as carbonio acid-which prevents the complete reduction of the ore. Furthermore, in the processes heretofore proposed in which the use of wateras was suggested the temperature at which it was proposed to use the gas was not sufficiently high for the complete reduction of the ore. Furthermore, these processes contemplated the reduction of the ore without the addition of carbon.

The object of this invention is to provide a new and improved process for reducing iron ore by the production of gases containing carbon monoxid and hydrogen at temperatures sufficiently high to reduce the ores when brought into contact therewith, this temperature being in the case of iron ores about 1,100o centigrade.

With this and other objects in view the invention consists in the process which is hereinafter described and then more specifically setforth in the claims hereunto appended.

In order that the process may be fully understood, the same will be described in conneetionlwith an apparatus which is capacitated for carrying it out. It is to be understood, however, that the process is in no way dependent upon the particular form of appa- ,ratus which is herein shown and described.A

In the accompanying drawings, Figure 1 is a plan view, partly in section, of a form of furnace suitable for carrying out the process which forms the invention. Fig. 2 is a longitudinal section of the same.

In order to successfully reduce iron ore, the gas employed in the reduction should be free from oxidizing material and should be employed at a temperature of about 1,100o centigrade. According to the present invention the gas which is to be employed in reducing the ore is obtained by a proper treat- Specification of Letters Patent. Applicati'm filed June 24, 1

This gas, however, contains oxidiz- Patented Feb. 13, 1906. 908. Serial No. 162,876.

ment of air mixed with water or steam. The preferred mode of obtaining this mix'turc'is to spray water into a current of air, which is afterward raised to a temperature which must at least be high enough to convert the water into steam. In practically carrying out the invention, however, the temperature to which the mixture of air and steam is subjected will be as high as possible. It may be here remarked that it is desirable to intro-v duce into the air as large a proportion of water as possible in order to form as much hydrogen as possible; but the proportion of air must be high enough to maintain the gases at a proper reducing temperature. In other words, the proportion of air to water or steam must be so regulated that the resulting gases will be delivered to the furnace at a proper reducing temperature, which with iron ores is about 1,100 centigrade. After raising the temperature of the mixture of air and water or steam in the manner described the air and steam is then brought into contact with carbon in order to form carbon monoxid and hydrogen. This can best be accomplished by bringing the air and steam in its heated condition into contact with a mass of glowmg coke. The contact of the heated steam and air with the glowing coke produces the gases described-that is to say, hydrogen and carbon monoxid; but it also produces a small percentage of carbonic acid, which is objectionable for' the reason that the carbonic acid prevents the com-plete reduction of the ore. In order to change this carbonio acid into monoxid, the gas is kept in contact with a mass of glowing coke until the carbonic acid has taken up carbon enough to form carbon monoxid. This not only frees the gas from the objectionable carbonio acid, but by changing it into carbon monoxid further increases tIie reductive capacity of the gas, so that its efficiency is increased. In order to enable this gas, which, as before indicated, contains hydrogen and carbon monoxid, to reduce the iron ore, it is desirable to use in reducing the ore a small percentage of carbon, inasmuch as this carbon infiuences the reductive capacity of the carbon monoxid. The desired small percentage ol' carbon may be obtained and utilized in various ways. Preferably, however, the gas after being freed from the carbonio acid in the manner described is brought into contact with the ore, which has mixed therewith a small quantity of solid carbon-say about IOC three per cent. i mixed with the or(` in any desired manner; but preferably the ore and carbon will be formed into briquets. The use of this small percentage of'carbony in reducmg the ore is to practically remove all traces of oxygen from the ore. The effect thus produced by using this small percentage of carbon'm reducing the ore is to be carefully distinguished from the well-known blast-furnace process in which a comparativel large percentage of carbon is mixed with t ie ore. The mixing of a large percentage of carbon with the ore carburizes the ore and converts it into pig-iron, whereas the object of the present process is to produce wrought-iron, which object would be defeated if a large percentage of carbon were mixed with ore prior to reduction. It may happen that the gases resulting vfrom the action of the glowing coke on the air and steam will contain an objectionable percentage of sulfur, due to the presence of sulfur in the coke, and when this is the'case it is desirable to purify the gases by removing the sulfur. While this may be effected 1n various ways, it can best be accomplished by mixing limestone with the coke in the chambers of the gas-producer. This will preferably be done by mixing the proper percentage-say about ten per cent, of limestone with the coke in the gasproducer and with the coke in the charging receptacles or hoppers, so that as the coke is renewed in the gas-producer the proper percentage of limestone will be fed in with it. The lime in the limestone combines with the sulfur in the coke, thus forming calcium vsulfid, and at the same time the small percentage of carbonio acid present in the lime will unite with the carbon in the glowing coke to form carbon monoxid. The mixing of lime with the glowing coke has the further beneicial effect of making slag of the silicate in the coke. Y

In the apparatus illustrated in the drawings there is shown a reducing-furnace A, which is connected by a channel B with a gas-producer D, said producer consisting of a chamber D. The hopper through 'which the coke or coke and limestone when limestone is mixed with the coke are introduced in the chamber D is marked C, this hopper being mounted above the chamber so as to discharge directly thereinto. A chamber F is provided which contains sets of iron pipes F', into which airis forced by meansof a blower E, the conduit leading from the v blower to the pipes F being marked E.

G indicates a'water-pipe., which is provided at its ends witn a suitable spray through which water may be sprayed into the pipes F. A series of these pipes G may be employed, the point of connection at which the sprays enter the pipes being This solid carbon may bek shown are heated by means of the resulting gases from the furnace A. The ases lare burned in a combustion-chamber by contact with air, which is led into the chamber through an opening indicated at J. The products are led out 4from the chamber F through the pipe or stack K.

, In practically carrying outv the invention as high a temperature as possible is maintained in the chamber F, because the higher the temperature in this Ichamber the more water rcan be introduced into the current of air which asses therethrough. It is desirable that the temperature maintained in this chamber F should not be less than 400 centigrade. The air and steam is led from the pipes F by means of a pipe L, fromwhich it is forced through twyersM into the chamber of the gas-producer D. This as-producer contains incandescent coke. mixed air and steam strikes-this incandescent coke, a gas is formed containing nitrogen, hydrogen, carbon monoxid, and a small amount of carbonio acid. In order to free the gas from the carbonio acid, it is led through the channel B, which also contains incandescent coke, said channel being supplied with coke from a hopper C. This channel is given an upward bend, as shown, so that the gas will pass more readily therethrough, and is sufiiciently long so that the carbonicacid gas will remain a suflicient length of time in contact with the incandescent coke to take up the molecule of carbon necessary to convert it into carbon monoxid. When, as before indicated, there is limestone mixed with the coke, the lime will unite with the sulfur in the coke, forming calcium sulid, whereby pure Vgases are generated, ,and the limestone will also act to slag the silicate in the coke. The gas passes from the channel B into the furnace A and is there brought into contact with ore, which, as before pointed out, preferably has mixed with it from two to-three per cent. of solid carbon. After the as has passed through the ore it will be led ack, as before described, into the combustion-chamber, so that the reducing process is a continuous one.

hen the y marked G. The pipes F" in the apparatus 65 IOO IIO

The temperature in the lower part of the gasproducer D may be roughl estimated at about 1,6000 centigrade. T e temperature at which the gas is utilized in the furnace A, however, need not be above 1,100O centigrade. The temperature in the gas producer D will of course be lowered by an amount corresponding to the amount of steam which is introduced into it with the air. This amount of steam is, however, controlled by the amount of water introduced into the air by the spray G. In carrying out the invention, therefore, the spray G should be so controlled that the temperature of the gas at the end of the channel B will not be lowered below or raised above about 1,1000 centigrade, which can be readily eifected by watching the temperature of the gases at the mouth oi the channel B and regulating the spray in accordance therewith. Under ordinary conditions the amount of water introduced will be from four per cent. to six er cent.

The .process above descri )ed can be carried on at a low cost and is of high elliciency. l1`urthermore, ore which cannot be reduced in ordinary blast-furnaces because it contains titanic acid can be reduced by this process. This process can also be advantageously used in reducing ores containing phosphoric acid. In blast-furnaces on account of the high temperature the phosphoric acid is converted into phosphorus, which enters the iron. At the comparatively low temperatures employed in this process, however, the phosphoric acid is only slightly reduced, so that the resulting iron contains but little phosphorus.

What is claimed is- 1. The process of reducing iron ore which consists in subjecting air mixed with steam in a continuous heated current to the action of glowing coke to form carbon monoxid and hydrogen and so regulating the proportion of air to the steam that the resulting gases will have a temperature of about 1,100O centigrade and finally passing the gases at said temperature through the ores to be reduced, substantially as described.

2. The process of reducing iron ore which consists in subjecting air mixed with steam in a continuous heated current to the action of glowing coke having limestone mixed therewith, whereby carbon monoxid and hydrogen free from sulfur are formed and so regulating the proportion of air to the steam that the resulting gases will have a temperature of about 1,1000 centigrade, and finally passing the gases at said temperature through the ores to be reduced, substantially as described.

3. The process of reducing iron ore which consists in introducing water into a continuous current of air, heating the Inixed air and water to form steam, passing the air and steam through glowing coke to form carbon monoxid and hydrogen, regulating the proportion of air to the steam so that the resulting gases will have a temperature of about 1,1000 centigrade and passing the gases at said temperature throu h the ores to be reduced, substantially as escribed.

4. The process of reducing iron ore which consists in introducing water into a continuous current of air, heating the mixed air and water to form steam, passing the air and steam through glowing coke mixed with limestone to form carbon monoxid and hydrogen free from sulfur, regulating the proportion of air to the steam so that the resultmg gases will have a temperature of about 1,1000` centigrade and passing gases at 'said temperature through the ores to be reduced, substantially as described.

5. The process of reducing iron ore which consists in subjecting air mlxed with steam in a continuous heated current to the action of glowing coke to form carbon monoxid and hydrogen and so regulating the proportion of air to the steam that the resultmg gases will have a temperature of about 1,1000 centigrade and finally causing the gases at said temperature to act upon the ores to be reduced in the presence of a .small percentage of carbon, substantially as described.

6. The process of reducing iron ore which consists in subjecting air mixed with steam in a continuous heated current to the action of glowing coke mixed With limestone to form carbon monoxid and h drogen free from sulfur and so regulating t e proportion of air to the steam that the resulting gases will have a temperature of about 1,1000 centigrade and finally causing the gases at said temperature to act u on the ores to be reduced in the presence o a small percentage of carbon, substantially as described.

7. The process of reducing iron ore which consists in introducing water into a continuous current of air, heating the mixed air and water to form steam, assing the air and ,steam through glowing coiie to form carbon monoxid and hydrogen,regulating the roportion of air to the steam so that the resu ting gases will have a temperature of about 1,1000 centigrade and finally causing the gases'at said temperature to act upon the ores to be reduced in the presence of a small percentage of carbon, substantially as described.

8. The process of reducing iron ore which consists in introducing water into a continuous current of air, heating the mixed air and water to form steam, passing the air and steam through glowing coke mixed with limestone to form carbon monoxid and hydrogen free from sulfur, regulating the proportion of air to the steam so that the resultlng gases will have a tem erature of about 1,1000 centigrade and nally causing the gases at said temperature to act upon the ores to be reduced in the presence of a small percentage of carbon, substantially as described.

9. The process of reducing iron ore which consists in spraying water into a current of air, raising t e temperature of the mixed air and water to form air and steam, passing the air and steam through incandescent carbon to form carbon monoxid and hydrogen, and subjecting the gases thus formed to the action of the incandescent carbon, regulating the proportion of air to steam so that the resultmg. gases will have a temperature of about 1,1000 centigrade, and then causing the gases IIO at said temperature to act upon the ores to I be reduced in the presence of a small ercentage of carbon, substantially as descri ed.

grado, und thon causingr the gases at said temperature to not upon the orcs to'be reduced in tho presence oi' s smell percentage of carbon7 substantially :is described.

In testimony whereof l have hereunto set my hand in the prescncc of two subscribing witnesses,

GUSTAF M. WESTMAN.

Witnesses:

JAMEs Q. Riom, W II. KENNEDY 

